• Berggren, R., B. Bolin, and C.-G. Rossby, 1949: An aerological study of zonal motion, its perturbations and break-down. Tellus, 1, 1437, https://doi.org/10.3402/tellusa.v1i2.8501.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Chen, L., J. Francis, and E. Hanna, 2018: The “warm-Arctic/cold-continents” pattern during 1901–2010. Int. J. Climatol., 38, 52455254, https://doi.org/10.1002/joc.5725.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Chen, X., D. Luo, S. Feldstein, and S. Lee, 2018: Impact of winter Ural blocking on Arctic sea ice: Short-time variability. J. Climate, 31, 22672282, https://doi.org/10.1175/JCLI-D-17-0194.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Cheung, H. N., W. Zhou, Y. Shao, W. Chen, H. Y. Mok, and M. C. Wu, 2013: Observational climatology and characteristics of wintertime atmospheric blocking over Ural–Siberia. Climate Dyn., 41, 6379, https://doi.org/10.1007/s00382-012-1587-6.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Cohen, J., and Coauthors, 2014: Recent Arctic amplification and extreme mid-latitude weather. Nat. Geosci., 7, 627637, https://doi.org/10.1038/ngeo2234.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Cohen, J., and Coauthors, 2018: Arctic change and possible influence on mid-latitude climate and weather. U.S. CLIVAR Rep. 2018-1, 41 pp., https://doi.org/10.5065/D6TH8KGW.

    • Crossref
    • Export Citation
  • Comiso, J. C., 2006: Abrupt decline in the Arctic winter sea ice cover. Geophys. Res. Lett., 33, L18504, https://doi.org/10.1029/2006GL027341.

  • Dai, A., J. C. Fyfe, S.-P. Xie, and X. Dai, 2015: Decadal modulation of global-mean temperature by internal climate variability. Nat. Climate Change, 5, 555559, https://doi.org/10.1038/nclimate2605.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Davini, P., C. Cagnazzo, S. Gualdi, and A. Navarra, 2012: Bidimensional diagnostics, variability, and trends of Northern Hemisphere blocking. J. Climate, 25, 64966509, https://doi.org/10.1175/JCLI-D-12-00032.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Dee, D. P., and Coauthors, 2011: The ERA-Interim reanalysis: Configuration and performance of the data assimilation system. Quart. J. Roy. Meteor. Soc., 137, 553597, https://doi.org/10.1002/qj.828.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Diao, Y., J. Li, and D. Luo, 2006: A new blocking index and its application: Blocking action in the Northern Hemisphere. J. Climate, 19, 48194839, https://doi.org/10.1175/JCLI3886.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Francis, J. A., and S. J. Vavrus, 2012: Evidence linking Arctic amplification to extreme weather in mid-latitudes. Geophys. Res. Lett., 39, L06801, https://doi.org/10.1029/2012GL051000.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Gillett, N. P., and Coauthors, 2008: Attribution of polar warming to human influence. Nat. Geosci., 1, 750754, https://doi.org/10.1038/ngeo338.

  • Gu, S., Y. Zhang, Q. Wu, and X. Yang, 2018: The linkage between Arctic sea ice and midlatitude weather: In the perspective of energy. J. Geophys. Res. Atmos., 123, 11 53611 550, https://doi.org/10.1029/2018JD028743.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Hassanzadeh, P., Z. Kuang, and B. F. Farrell, 2014: Responses of midlatitude blocks and wave amplitude to changes in the meridional temperature gradient in an idealized dry GCM. Geophys. Res. Lett., 41, 52235232, https://doi.org/10.1002/2014GL060764.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Hoskins, B. J., M. E. McIntyre, and A. W. Robertson, 1985: On the use and significance of isentropic potential vorticity maps. Quart. J. Roy. Meteor. Soc., 111, 877946, https://doi.org/10.1002/qj.49711147002.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Hurrell, J. W., and Coauthors, 2013: The Community Earth System Model: A framework for collaborative research. Bull. Amer. Meteor. Soc., 94, 13391360, https://doi.org/10.1175/BAMS-D-12-00121.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Iwasaki, T., T. Shoji, Y. Kanno, M. Sawada, M. Ujiie, and K. Takaya, 2014: Isentropic analysis of polar cold airmass streams in the Northern Hemispheric winter. J. Atmos. Sci., 71, 22302243, https://doi.org/10.1175/JAS-D-13-058.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Ji, L., and S. Tibaldi, 1983: Numerical simulation of a case of blocking: The effects of orography and land–sea contrast. Mon. Wea. Rev., 111, 20682086, https://doi.org/10.1175/1520-0493(1983)111<2068:NSOACO>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Kelleher, M., and J. Screen, 2018: Atmospheric precursors of and response to anomalous Arctic sea ice in CMIP5 models. Adv. Atmos. Sci., 35, 2737, https://doi.org/10.1007/s00376-017-7039-9.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Kug, J.-S., and Coauthors, 2015: Two distinct influences of Arctic warming on cold winters over North America and East Asia. Nat. Geosci., 8, 759762, https://doi.org/10.1038/ngeo2517.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Li, S. L., 2004: Influence of the northwest Atlantic SST anomaly on the circulation over the Ural Mountains. J. Meteor. Soc. Japan, 82, 971988, https://doi.org/10.2151/jmsj.2004.971.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Luo, B., D. Luo, L. Wu, L. Zhong, and I. Simmonds, 2017: Atmospheric circulation patterns which promote winter Arctic sea ice decline. Environ. Res. Lett., 12, 054017, https://doi.org/10.1088/1748-9326/aa69d0.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Luo, D., 2000: Planetary-scale baroclinic envelope Rossby solitons in a two-layer model and their interaction with synoptic-scale eddies. Dyn. Atmos. Oceans, 32, 2774, https://doi.org/10.1016/S0377-0265(99)00018-4.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Luo, D., 2005: A barotropic envelope Rossby soliton model for block–eddy interaction. Part I: Effect of topography. J. Atmos. Sci., 62, 521, https://doi.org/10.1175/1186.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Luo, D., and J. Li, 2000: Barotropic interaction between planetary and synoptic-scale waves during the life cycles of blockings. Adv. Atmos. Sci., 17, 649670, https://doi.org/10.1007/s00376-000-0026-5.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Luo, D., J. Cha, L. Zhong, and A. Dai, 2014: A nonlinear multiscale interaction model for atmospheric blocking: The eddy-blocking matching mechanism. Quart. J. Roy. Meteor. Soc., 140, 17851808, https://doi.org/10.1002/qj.2337.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Luo, D., Y. Yao, and A. Dai, 2015a: Decadal relation between European blocking and North Atlantic Oscillation during 1978–2011. Part I: Atlantic conditions. J. Atmos. Sci., 72, 11521173, https://doi.org/10.1175/JAS-D-14-0039.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Luo, D., Y. Yao, and A. Dai, 2015b: Decadal relation between European blocking and North Atlantic Oscillation during 1978–2011. Part II: A theoretical model study. J. Atmos. Sci., 72, 11741199, https://doi.org/10.1175/JAS-D-14-0040.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Luo, D., Y. Xiao, Y. Yao, A. Dai, I. Simmonds, and C. L. E. Franzke, 2016a: Impact of Ural blocking on winter warm Arctic–cold Eurasian anomalies. Part I: Blocking-induced amplification. J. Climate, 29, 39253947, https://doi.org/10.1175/JCLI-D-15-0611.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Luo, D., Y. Xiao, Y. Diao, A. Dai, C. L. E. Franzke, and I. Simmonds, 2016b: Impact of Ural Blocking on winter warm Arctic–cold Eurasian anomalies. Part II: The link to the North Atlantic Oscillation. J. Climate, 29, 39493971, https://doi.org/10.1175/JCLI-D-15-0612.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Luo, D., X. Chen, A. Dai, and I. Simmonds, 2018a: Changes in atmospheric blocking circulations linked with winter Arctic warming: A new perspective. J. Climate, 31, 76617678, https://doi.org/10.1175/JCLI-D-18-0040.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Luo, D., X. Chen, and S. Feldstein, 2018b: Linear and nonlinear dynamics of North Atlantic Oscillations: A new thinking of symmetry breaking. J. Atmos. Sci., 75, 19551977, https://doi.org/10.1175/JAS-D-17-0274.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Marsh, D. R., M. J. Mills, D. E. Kinnison, J. Lamarque, N. Calvo, and L. M. Polvani, 2013: Climate change from 1850 to 2005 simulated in CESM1(WACCM). J. Climate, 26, 73727391, https://doi.org/10.1175/JCLI-D-12-00558.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • McCusker, K. E., J. C. Fyfe, and M. Sigmond, 2016: Twenty-five winters of unexpected Eurasian cooling unlikely due to Arctic sea-ice loss. Nat. Geosci., 9, 838842, https://doi.org/10.1038/ngeo2820.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Meleshko, V. P., V. M. Kattsov, V. M. Mirvis, A. V. Baidin, T. V. Pavlova, and V. A. Govorkova, 2018: Is there a link between Arctic sea ice loss and increasing frequency of extremely cold winters in Eurasia and North America? Synthesis of current research. Russ. Meteor. Hydrol., 43, 743755, https://doi.org/10.3103/S1068373918110055.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Mori, M., M. Watanabe, H. Shiogama, J. Inoue, and M. Kimoto, 2014: Robust Arctic sea-ice influence on the frequent Eurasian cold winters in past decades. Nat. Geosci., 7, 869873, https://doi.org/10.1038/ngeo2277.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Newson, R. L., 1973: Response of general circulation model of the atmosphere to removal of the Arctic ice-cap. Nature, 241, 3940, https://doi.org/10.1038/241039b0.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Outten, S., and I. Esau, 2012: A link between Arctic sea ice and recent cooling trends over Eurasia. Climatic Change, 110, 10691075, https://doi.org/10.1007/s10584-011-0334-z.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Overland, J. E., and M. Wang, 2018: Arctic–midlatitude weather linkages in North America. Polar Sci., 16, 19, https://doi.org/10.1016/j.polar.2018.02.001.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Overland, J. E., J. A. Francis, R. Hall, E. Hanna, S. Kim, and T. Vihma, 2015: The melting Arctic and mid-latitude weather patterns: Are they connected? J. Climate, 28, 79177932, https://doi.org/10.1175/JCLI-D-14-00822.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Overland, J. E., and Coauthors, 2016: Nonlinear response of mid-latitude weather to the changing Arctic. Nat. Climate Change, 6, 992998, https://doi.org/10.1038/nclimate3121.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Petoukhov, V., and V. A. Semenov, 2010: A link between reduced Barents-Kara sea ice and cold winter extremes over northern continents. J. Geophys. Res., 115, D21111, https://doi.org/10.1029/2009JD013568.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Pfahl, S., C. Schwierz, M. Croci-Maspoli, C. M. Grams, and H. Wernli, 2015: Importance of latent heat release in ascending air streams for atmospheric blocking. Nat. Geosci., 8, 610615, https://doi.org/10.1038/ngeo2487.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Rex, D. F., 1950: Blocking action in the middle troposphere and its effect upon regional climate. I. An aerological study of blocking action. Tellus, 2, 196211, https://doi.org/10.3402/tellusa.v2i3.8546.

    • Search Google Scholar
    • Export Citation
  • Sato, K., J. Inoue, and M. Watanabe, 2014: Influence of the Gulf Stream on the Barents Sea ice retreat and Eurasian coldness during early winter. Environ. Res. Lett., 9, 084009, https://doi.org/10.1088/1748-9326/9/8/084009.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Screen, J. A., and I. Simmonds, 2010: The central role of diminishing sea ice in recent Arctic temperature amplification. Nature, 464, 13341337, https://doi.org/10.1038/nature09051.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Screen, J. A., T. J. Bracegirdle, and I. Simmonds, 2018: Polar climate change as manifest in atmospheric circulation. Curr. Climate Change Rep., 4, 383395, https://doi.org/10.1007/s40641-018-0111-4.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Shepherd, T. G., 2016: Effect of a warming Arctic. Science, 353, 989990, https://doi.org/10.1126/science.aag2349.

  • Shoji, T., Y. Kanno, and T. Iwasaki, 2014: An isentropic analysis of the temporal evolution of East Asian cold air outbreaks. J. Climate, 27, 93379348, https://doi.org/10.1175/JCLI-D-14-00307.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Simmonds, I., 2015: Comparing and contrasting the behaviour of Arctic and Antarctic sea ice over the 35 year period 1979–2013. Ann. Glaciol., 56, 1828, https://doi.org/10.3189/2015AoG69a909.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Simmonds, I., 2018: What causes extreme hot days in Europe? Environ. Res. Lett., 13, 071001, https://doi.org/10.1088/1748-9326/aacc78.

  • Simmonds, I., and P. D. Govekar, 2014: What are the physical links between Arctic sea ice loss and Eurasian winter climate? Environ. Res. Lett., 9, 101003, https://doi.org/10.1088/1748-9326/9/10/101003.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Smith, K. L., R. R. Neely, D. R. Marsh, and L. M. Polvani, 2014: The Specified Chemistry Whole Atmosphere Community Climate Model (SC-WACCM). J. Adv. Model. Earth Syst., 6, 883901, https://doi.org/10.1002/2014MS000346.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Steele, M., W. Ermold, and J. Zhang, 2008: Arctic Ocean surface warming trends over the past 100 years. Geophys. Res. Lett., 35, L02614, https://doi.org/10.1029/2007GL031651.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Stroeve, J. C., and Coauthors, 2011: Sea ice response to an extreme negative phase of the Arctic Oscillation during winter 2009/2010. Geophys. Res. Lett., 38, L02502, https://doi.org/10.1029/2010GL045662.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Sun, L., J. Perlwitz, and M. Hoerling, 2016: What caused the recent “warm Arctic, cold continents” trend pattern in winter temperatures? Geophys. Res. Lett., 43, 53455352, https://doi.org/10.1002/2016GL069024.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Sung, M.-K., S.-H. Kim, B.-M. Kim, and Y.-S. Choi, 2018: Interdecadal variability of the warm Arctic and cold Eurasia pattern and its North Atlantic origin. J. Climate, 31, 57935810, https://doi.org/10.1175/JCLI-D-17-0562.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Tibaldi, S., and F. Molteni, 1990: On the operational predictability of blocking. Tellus, 42A, 343365, https://doi.org/10.3402/tellusa.v42i3.11882.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Vihma, T., 2014: Effects of Arctic sea ice decline on weather and climate: A review. Surv. Geophys., 35, 11751214, https://doi.org/10.1007/s10712-014-9284-0.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Walsh, J. E., 2014: Intensified warming of the Arctic: Causes and impacts on middle latitudes. Global Planet. Change, 117, 5263, https://doi.org/10.1016/j.gloplacha.2014.03.003.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Wilks, D. S., 2011: Statistical Methods in the Atmospheric Sciences, 2nd ed. Elsevier, 627 pp.

  • Woods, C., and R. Caballero, 2016: The role of moist intrusions in winter Arctic warming and sea ice decline. J. Climate, 29, 44734485, https://doi.org/10.1175/JCLI-D-15-0773.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Wu, Z., and T. Reichler, 2018: Towards a more Earth-like circulation in idealized models. J. Adv. Model. Earth Syst., 10, 14581469, https://doi.org/10.1029/2018ms001356.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Yang, Z., W. Huang, B. Wang, R. Chen, J. S. Wright, and W. Ma, 2018: Possible mechanisms for four regimes associated with cold events over East Asia. Climate Dyn., 51, 3556, https://doi.org/10.1007/s00382-017-3905-5.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Yao, Y., D. Luo, A. Dai, and I. Simmonds, 2017: Increased quasi-stationarity and persistence of Ural blocking and Eurasian extreme cold events in response to Arctic warming. Part I: Insight from observational Analyses. J. Climate, 30, 35493568, https://doi.org/10.1175/JCLI-D-16-0261.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Ye, K., T. Jung, and T. Semmler, 2018: The influences of the Arctic troposphere on the midlatitude climate variability and the recent Eurasian cooling. J. Geophys. Res. Atmos., 123, 10 16210 184, https://doi.org/10.1029/2018JD028980.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Yeh, T. C., 1949: On energy dispersion in the atmosphere. J. Meteor., 6, 116, https://doi.org/10.1175/1520-0469(1949)006<0001:OEDITA>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Zhang, P., Y. Wu, I. Simpson, K. L. Smith, X. Zhang, B. De, and P. Callaghan, 2018a: A stratospheric pathway linking a colder Siberia to Barents-Kara sea ice loss. Sci. Adv., 4, eaat6025, https://doi.org/10.1126/sciadv.aat6025.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Zhang, P., Y. Wu, and K. Smith, 2018b: Prolonged effect of the stratospheric pathway in linking Barents–Kara Sea sea ice variability to the midlatitude circulation in a simplified model. Climate Dyn., 50, 527539, https://doi.org/10.1007/s00382-017-3624-y.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Zhang, R., C. Sun, R. Zhang, L. Jia, and W. Li, 2018: The impact of Arctic sea ice on the inter-annual variations of summer Ural blocking. Int. J. Climatol., 38, 46324650, https://doi.org/10.1002/joc.5731.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Zhong, L., L. Hua, and D. Luo, 2018: Local and external moisture sources for the Arctic warming over the Barents–Kara Seas. J. Climate, 31, 19631982, https://doi.org/10.1175/JCLI-D-17-0203.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
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Weakened Potential Vorticity Barrier Linked to Recent Winter Arctic Sea Ice Loss and Midlatitude Cold Extremes

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  • 1 Key Laboratory of Regional Climate-Environment for Temperate East Asia, Institute of Atmospheric Physics, Chinese Academy of Sciences, and University of Chinese Academy of Sciences, Beijing, China
  • 2 NOAA/Pacific Marine Environmental Laboratory, Seattle, Washington
  • 3 School of Earth Sciences, The University of Melbourne, Victoria, Australia
  • 4 Lamont–Doherty Earth Observatory, Columbia University, Palisades, New York
  • 5 Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, Los Angeles, California
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Abstract

A winter Eurasian cooling trend and a large decline of winter sea ice concentration (SIC) in the Barents–Kara Seas (BKS) are striking features of recent climate changes. The question arises as to what extent these phenomena are related. A mechanism is presented that establishes a link between recent winter SIC decline and midlatitude cold extremes. Such potential weather linkages are mediated by whether there is a weak north–south gradient of background tropospheric potential vorticity (PV). A strong background PV gradient, which usually occurs in North Atlantic and Pacific Ocean midlatitudes, acts as a barrier that inhibits atmospheric blocking and southward cold air intrusion. Conversely, atmospheric blocking is more persistent in weakened PV gradient regions over Eurasia, Greenland, and northwestern North America because of weakened energy dispersion and intensified nonlinearity. The small climatological PV gradients over mid- to high-latitude Eurasia have become weaker in recent decades as BKS air temperatures show positive trends due to SIC loss, and this has led to more persistent high-latitude Ural-region blocking. These factors contribute to increased cold winter trend in East Asia. It is found, however, that in years when the winter PV gradient is small the East Asian cold extremes can even occur in the absence of large negative SIC anomalies. Thus, the magnitude of background PV gradient is an important controller of Arctic–midlatitude weather linkages, but it plays no role if Ural blocking is not present. Thus, the “PV barrier” concept presents a critical insight into the mechanism producing cold Eurasian extremes and is hypothesized to set up such Arctic–midlatitude linkages in other locations.

Supplemental information related to this paper is available at the Journals Online website: https://doi.org/10.1175/JCLI-D-18-0449.s1.

© 2019 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).

Corresponding author: Dr. Dehai Luo, ldh@mail.iap.ac.cn

Abstract

A winter Eurasian cooling trend and a large decline of winter sea ice concentration (SIC) in the Barents–Kara Seas (BKS) are striking features of recent climate changes. The question arises as to what extent these phenomena are related. A mechanism is presented that establishes a link between recent winter SIC decline and midlatitude cold extremes. Such potential weather linkages are mediated by whether there is a weak north–south gradient of background tropospheric potential vorticity (PV). A strong background PV gradient, which usually occurs in North Atlantic and Pacific Ocean midlatitudes, acts as a barrier that inhibits atmospheric blocking and southward cold air intrusion. Conversely, atmospheric blocking is more persistent in weakened PV gradient regions over Eurasia, Greenland, and northwestern North America because of weakened energy dispersion and intensified nonlinearity. The small climatological PV gradients over mid- to high-latitude Eurasia have become weaker in recent decades as BKS air temperatures show positive trends due to SIC loss, and this has led to more persistent high-latitude Ural-region blocking. These factors contribute to increased cold winter trend in East Asia. It is found, however, that in years when the winter PV gradient is small the East Asian cold extremes can even occur in the absence of large negative SIC anomalies. Thus, the magnitude of background PV gradient is an important controller of Arctic–midlatitude weather linkages, but it plays no role if Ural blocking is not present. Thus, the “PV barrier” concept presents a critical insight into the mechanism producing cold Eurasian extremes and is hypothesized to set up such Arctic–midlatitude linkages in other locations.

Supplemental information related to this paper is available at the Journals Online website: https://doi.org/10.1175/JCLI-D-18-0449.s1.

© 2019 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).

Corresponding author: Dr. Dehai Luo, ldh@mail.iap.ac.cn

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